Polyvinyl chloride is one of the most widely used polymers worldwide. The common abbreviation of polyvinyl chloride is PVC which will be used in the following. Depending on the additives used for compounding, the properties of PVC can vary to a large extent. PVC foams are also known. PVC is generally classified into unplasticized or rigid PVC and plasticized or flexible PVC containing plasticizer. The common abbreviations for unplasticized and plasticized PVC are PVC-u and PVC-p, respectively, which are used in the following.
Application areas of flexible PVC are for instance rock shield pads, roofing and waterproofing membranes, waterstops and waterbars, pipes and hosepipes, joint sealings and cable coatings. Rock shield pads made of non-woven mats consisting of small diameter (approximately 1.25 mm) strands of flexible PVC are suitable for pipeline protection and commercially available e.g. from Sika Greenstreak Group, Inc. under the tradename TUFF-N-NUFF®.
While the existing products show satisfactory properties, reduction of material consumption and costs is always a task, in particular when considering mass products. A reduction of the product weight would allow easier installation and less CO2 emission during transport. Of course, improvements in this regard by altering the product composition or structure should not significantly deteriorate the desired properties and the appearance of the existing products.
Different approaches are possible to reduce material costs or reduce product weight, such as making the product thinner or the use of alternative raw materials. However, these approaches often sacrifice on deteriorated impact properties or a different appearance of the product.
EP 2612881 A1 relates to a resin composition for preparing foamed rigid polymer products, comprising at least one polymer resin which may be polyvinyl chloride, a surface-treated calcium carbonate, and a blowing agent.
US 2012/208963 A1 describes foamable halogenated polymers such as polyvinyl chloride comprising a specific multi-stage emulsion processing aid polymer.
EP 1065242 A1 is concerned with an expandable vinyl chloride resin composition comprising 100 parts by weight of a vinyl chloride resin, 5 to 30 parts by weight of a (meth)acrylic ester polymer, as a processing aid, and 2 to 25 parts by weight of a thermally decomposable inorganic foaming agent.
WO 02/20660 A2 relates to polyvinyl chloride resin compositions for increasing the degree of whiteness in finished polyvinyl chloride foams, the resin compositions containing sulfur compounds.